Japanese Patent Serial No. 3199296, issued by The Japan Patent Office in 2001, teaches placing a number of the batteries side by side under a floor panel of a vehicle so as to mount as many batteries as possible on the vehicle.
The batteries are arranged side by side in a flat plane in a vehicle transverse direction as well as a vehicle longitudinal direction to form a group of batteries. A center of gravity of the group of batteries is located around an intersecting point of a median of the group of batteries in the vehicle transverse direction and a median of the same in the vehicle longitudinal direction.